[PATCH] nvmet: fix false keep-alive timeout when a controller is torn down

[Sagi Grimberg]

Controller teardown flow may take some time in case it has many I/O
queues, and the host may not send us keep-alive during this period.
Hence reset the traffic based keep-alive timer so we don't trigger
a controller teardown as a result of a keep-alive expiration.

Reported-by: Yi Zhang <yi.zhang at redhat.com>
Signed-off-by: Sagi Grimberg <sagi at grimberg.me>
---
 drivers/nvme/target/core.c  | 16 ++++++++++++----
 drivers/nvme/target/nvmet.h |  2 +-
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index 1853db38b682..e991b4671aeb 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -388,10 +388,10 @@ static void nvmet_keep_alive_timer(struct work_struct *work)
 {
 	struct nvmet_ctrl *ctrl = container_of(to_delayed_work(work),
 			struct nvmet_ctrl, ka_work);
-	bool cmd_seen = ctrl->cmd_seen;
+	bool reset_tbkas = ctrl->reset_tbkas;
 
-	ctrl->cmd_seen = false;
-	if (cmd_seen) {
+	ctrl->reset_tbkas = false;
+	if (reset_tbkas) {
 		pr_debug("ctrl %d reschedule traffic based keep-alive timer\n",
 			ctrl->cntlid);
 		schedule_delayed_work(&ctrl->ka_work, ctrl->kato * HZ);
@@ -804,6 +804,14 @@ void nvmet_sq_destroy(struct nvmet_sq *sq)
 	percpu_ref_exit(&sq->ref);
 
 	if (ctrl) {
+		/*
+		 * teardown flow may take some time, and the host
+		 * may not send us keep-alive during this period,
+		 * hence reset the traffic based keep-alive timer
+		 * so we don't trigger a controller teardown as
+		 * a result of a keep-alive expiration.
+		 */
+		ctrl->reset_tbkas = true;
 		nvmet_ctrl_put(ctrl);
 		sq->ctrl = NULL; /* allows reusing the queue later */
 	}
@@ -952,7 +960,7 @@ bool nvmet_req_init(struct nvmet_req *req, struct nvmet_cq *cq,
 	}
 
 	if (sq->ctrl)
-		sq->ctrl->cmd_seen = true;
+		sq->ctrl->reset_tbkas = true;
 
 	return true;
 
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index d69a409515d6..53aea9a8056e 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -167,7 +167,7 @@ struct nvmet_ctrl {
 	struct nvmet_subsys	*subsys;
 	struct nvmet_sq		**sqs;
 
-	bool			cmd_seen;
+	bool			reset_tbkas;
 
 	struct mutex		lock;
 	u64			cap;
-- 
2.27.0